C# Fundamentals: Development for Absolute Beginners - Quick Overview of the Visual C# Express Edition IDE - 04

Quick Overview of the Visual C# Express Edition IDE - 04

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C# Fundamentals: Development for Absolute Beginners - Dissecting the First C# Program You Created - 03

Dissecting the First C# Program You Created - 03

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C# Fundamentals: Development for Absolute Beginners - Creating Your First C# Program - 02

Creating Your First C# Program - 02

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C# Fundamentals: Development for Absolute Beginners - Series Introduction - 01

Series Introduction - 01

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C# Fundamentals Important Update!

C# 18 – String Manipulation – Creating a Palindrome Checker

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In this tutorial we will be doing some string manipulation by creating a program called Palindrome Checker that will determine if a word or a string of letters is a palindrome.

Before we proceed we need to know what is the meaning of a palindrome.

What is a palindrome? According to Wikipedia:

“A palindrome is a word, phrase, number, or other sequence of units that may be read the same way in either direction, with general allowances for adjustments to punctuation and word dividers.”

http://en.wikipedia.org/wiki/Palindrome

Which means a word is read the same whether it’s in normal order or in reversed order.

e.g. 

kayak

nissin

madam

Ok let’s begin.

1.     Create a new console project.

2.     Add the following code inside of class Program.

static void Main(string[] args)

       {

            string input;

            Console.WriteLine("Welcome to Palindrome Checker");

            Console.WriteLine("- The software will check if your input is a palindrome. -");

            Console.WriteLine("");

            Console.Write("Enter a string: ");

            input = Console.ReadLine();

            if (IsPalindrome(input))           

                Console.WriteLine(input + " is a palindrome.");

            else

                Console.WriteLine(input + " is a not palindrome.");

            Console.WriteLine("");

            Console.WriteLine("Press any key to exit.");

            Console.ReadLine();

        }

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        private static bool IsPalindrome(string input)

        {

            string reverse = "";

            for (int i = input.Length-1; i >= 0; i--)

            {

                reverse = reverse + input[i];

            }

           

            if (input.Equals(reverse))

                return true;

            return false;

        }

3.     Press F5 to run the program. You output should be something similar below.

You have noticed in the output above that I entered the word “kayak” and pressed Enter. After that the result is shown which is “kayak is a palindrome” in this example.

What we will try to focus our attention now is for this function.

private static bool IsPalindrome(string input)

{

string reverse = "";

       for (int i = input.Length-1; i >= 0; i--)

       {

              reverse = reverse + input[i];

       }

            

       if (input.Equals(reverse))

              return true;

return false;

}

This is the main function that checks if a given string is a palindrome. It creates a variable ‘reverse’ that will hold the reversed string. It enters a loop which starts at the end of the string and then moves backwards one character at a time and stores that character to the ‘reverse’ variable.

After the reversal is complete the next step is to check whether the ‘input’ string is indeed equal to the ‘reverse’ string. If they are equal then the function should return true or false if its not.

Hope you enjoyed our simple and quick tutorial.

Be happy and keep coding!

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Learn C# Online - Summary of C# Tutorials

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C# 1 – Hello World

C# 2 – Variables

C# 3 - Variable Scope

C# 4 - What If?

C# 5 - What If? Or, Else ?

C# 6 - What If? Or, Else If....?

C# 7 - Switch statement

C# 8 - For loop statement

C# 9 - while-loop statement

C# 10 - do-while-loop statement

C# 11 - Arrays

C# 12 - Multidimensional Arrays - Multiplication Table

C# 13 - Collections - Todo List

C# 14 - Find the largest value in an array

C# 15 - Selection sort

C# 16 - Insertion Sort

C# 17 - Bubble Sort

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C# 17 - Bubble Sort

Implementing a sort using insertion sort algorithm.

1. Create a new console project.
2. Edit the Program.cs inside static void Main(string[] args) file as shown below.

static void Main(string[] args)

{

     int[] array = { 2, 3, 1, 9, 4, 7, 5, 8, 6, 10, 20, 12, 18, 11, 15, 16 };

          Console.Write("Before sort: ");

          PrintArray(array);

          Console.WriteLine();

          BubbleSort(array);

          Console.Write("After sort: ");

          PrintArray(array);

          Console.ReadLine();

}




private static void BubbleSort(int[] array)

{

     int temp;

     for (int i = array.Length; i >= 0 ; i--)

     {                

          for (int x = 0; x < array.Length - 1; x++)

          {

               if (array[x] > array[x + 1])

               {

                    temp = array[x];

                    array[x] = array[x + 1];

                    array[x + 1] = temp;

                }

           }

       }

}




private static void PrintArray(int[] array)

{

     for (int i = 0; i < array.Length; i++)

     {

          Console.Write(array[i] + " ");

     }

}


3. Press F5 to run and see the results.

4. Enjoy!

References:
http://www.sorting-algorithms.com/bubble-sort
http://en.wikipedia.org/wiki/Bubble_sort
http://www.algolist.net/Algorithms/Sorting/Bubble_sort

C# 16 - Insertion Sort

Implementing a sort using insertion sort algorithm.

1. Create a new console project.
2. Edit the Program.cs inside static void Main(string[] args) file as shown below.



static void Main(string[] args)
{           
     int[] array = { 2, 3, 1, 9, 4, 7 };
     Console.Write("Before sort: ");
     PrintArray(array);
     Console.WriteLine();
     InsertionSort(array);
     Console.Write("After sort: ");
     PrintArray(array);
     Console.ReadLine();
}


private static void InsertionSort(int[] array)
{
     /*
       for i = 2:n,
            for (k = i; k > 1 and a[k] < a[k-1]; k--) 
                 swap a[k,k-1]
                 → invariant: a[1..i] is sorted
            end
     */
     for (int i = 0; i < array.Length; i++)
     {
          for (int x = i; x < 0; x--)
          {
               if (array[x] < array[x - 1])
               {
                    int temp = array[x - 1];
                    array[x - 1] = array[x];
                    array[x] = temp;
               }
           }
      }
}


private static void PrintArray(int[] array)
{
       for (int i = 0; i < array.Length; i++)
       {
            Console.Write(array[i] + " ");
       }
}


3. Press F5 to run and see the results.

4. Thank you.

References:
http://en.wikipedia.org/wiki/Insertion_sort
http://www.sorting-algorithms.com/insertion-sort

C# 15 - Selection sort

Implementing a sort using selection sort algorithm.

1. Create a new console project.
2. Edit the Program.cs inside static void Main(string[] args) file as shown below.

static void Main(string[] args)
{
    int[] array = { 3, 2, 1, 4, 8 };
    Console.Write("Before sort: ");
    PrintArray(array);
    Console.WriteLine();
    SelectionSort(array);
    Console.Write("After sort : ");
    PrintArray(array);
    Console.WriteLine();

    Console.ReadLine();
}

private static void SelectionSort(int[] sortArray)
{
    int smallest = 0;
    int smallestIndex = 0;

     /* advance the position through the entire array */
     /*   (could do i < n-1 because single element is also min element) */
     for (int i = 0; i < sortArray.Length; i++)
     {
          smallest = sortArray[i];//the smallest value is at index 0
          smallestIndex = i;//store the index of the smallest value

           //find the index of the smallest value
                for (int x = i + 1; x < sortArray.Length; x++)
                {
                    if (sortArray[x] < sortArray[i])
                        smallestIndex = x;
                }

                //swap/exchange the smallest value found with last index
                sortArray[i] = sortArray[smallestIndex];
                sortArray[smallestIndex] = smallest;
            }
        }


private static void PrintArray(int[] array)
{
     for (int i = 0; i < array.Length; i++)
     {
          Console.Write(array[i] + " ");
     }
}


3. Press F5 to run and see the results.

4. Thank you.

Reference(s):
http://en.wikipedia.org/wiki/Selection_sort
http://www.sorting-algorithms.com/selection-sort

C# 13 - Find the smallest value in an array

1. Create a new console project.
2. Edit the Program.cs inside static void Main(string[] args) file as shown below.

static void Main(string[] args)
        {
            int[] array = { 3, 2, 1, 4, 8 };
            PrintArray(array);
            Console.WriteLine("Smallest Value: " + GetSmallestValue(array));

            Console.ReadLine();
        }


private static int GetSmallestValue(int[] array)
        {
            int smallest = array[0];

            for (int i = 0; i < array.Length; i++)
            {
                if (array[i] < smallest)
                    smallest = array[i];
            }

            return smallest;
        }

private static void PrintArray(int[] array)
        {
            for (int i = 0; i < array.Length; i++)
            {
                Console.Write(array[i] + " ");
            }
            Console.WriteLine();
        }



3. Press F5 to run and see the results.

4. Thank you.

C# 12 - Multidimensional Arrays - Multiplication Table

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1. Create a new console project.

2. Edit the Program.cs inside static void Main(string[] args) file as shown below.

static void Main(string[] args)

        {
            int[,] multiplicationTable = new int[11,11];
 
            for (int i = 1; i < 11; i++)
                for (int x = 1; x < 11; x++)
                    multiplicationTable[i, x] = i * x;
 
            Console.Write("x".PadRight(3) + "|");
            for (int i = 1; i < 11; i++)
            {
                Console.Write(i.ToString().PadRight(3) + "|");
            }
            Console.Write("\n");
            Console.WriteLine("--------------------------------------------");
 
            for (int i = 1; i < 11; i++)
            {
                Console.Write(i.ToString().PadRight(3) + "|");
                for (int x = 1; x < 11; x++)
                {
                    Console.Write(multiplicationTable[i, x].ToString().PadRight(3) + "|");
                }
                Console.Write("\n");
                Console.WriteLine("--------------------------------------------");
            }
 
            Console.ReadLine();
       }       

3. Press F5 to run and see the results.

4. Thank you.

Rectangular array is another type of array that allows you to define a table like array that has a row and column definition.

Syntax:

type[,] = new type[row,column];

type – can be any data type

row – is the number of rows for your table

column – is the number of columns for your table

e.g.

                int[,] mytable = new int[10, 5];

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C# 11 - Arrays

An array of sorts.

1. Create a new console project.
2. Edit the Program.cs inside static void Main(string[] args) file as shown below.

static void Main(string[] args)
{
     //declaring and initializing an array
     string[] theAvengers = new string[5];
     theAvengers[0] = "Iron Man";
     theAvengers[1] = "Thor";
     theAvengers[2] = "Captain America";
     theAvengers[3] = "Hawkeye";
     theAvengers[4] = "Hulk";
 
     Console.WriteLine("The Avengers!");
     Console.WriteLine("-------------------------");
     //loop through an array to access or modify its contents
     for (int i = 0; i < 5; i++)
     {
         Console.WriteLine(theAvengers[i]);
     }
 
     //another way of declaring and initializing an array
     //also another way is

    //string[] uncannyXMen = new string[] { "Wolverine", "Prof. X", "Cyclops", "Storm", "Beast" };

     string[] uncannyXMen = { "Wolverine", "Prof. X", "Cyclops", "Storm", "Beast" };
             
     Console.WriteLine("\nThe X-Men!");
     Console.WriteLine("-------------------------");

     //loop through an array to access in contents
     for (int i = 0; i < uncannyXMen.Length; i++)
     {
          Console.WriteLine(uncannyXMen[i]);
     }
 

     Console.WriteLine("Press any key to continue...");
     Console.ReadLine();
}

3. Press F5 to run and see the results.

4. Thank you.

Declaring an array allows you to store multiple items of a specific type. It syntax is:

type[] arrayName;

To learn more about arrays check these resources.

Arrays(C# Programming Guide)

Arrays tutorial

C# 10 - do-while-loop statement

1. Create a new console project.
2. Edit the Program.cs inside static void Main(string[] args) file as shown below.

   static void Main(string[] args)

        {

            int counter = 0;            

            while (counter < 10)

            {

                Console.WriteLine("Hello World from a while loop.");

                counter++;

            }

            Console.WriteLine("Press any key to continue...");

            Console.ReadLine();

            }

3. Press F5 to run and see the results.

5. Thank you.

The do- while-loop statement is used perform a piece of code multiple times as long as the condition set is evaluated to true. It executes code at least once. Its syntax is:

do

{

                //code to execute

}

while(<condition>);

C# 9 - while-loop statement

1. Create a new console project.
2. Edit the Program.cs inside static void Main(string[] args) file as shown below.

    class Program
    {
        static void Main(string[] args)
        {
            int counter = 0;
            
            while (counter < 10)
            {
                Console.WriteLine("Hello World from a while loop.");
                counter++;
            }
 
            Console.WriteLine("Press any key to continue...");
            Console.ReadLine();
        }
    }

3. Press F5 to run and see the results.

4. Thank you.


The while-loop statement is used perform a piece of code multiple times as long as the condition set is evaluated to true. Its syntax is:

while(<condition>)
{
    //code to execute
}

C# 8 - For loop statement

1. Create a new console project.
2. Edit the Program.cs inside static void Main(string[] args) file as shown below.

        static void Main(string[] args)
        {
            for (int i = 0; i < 10; i++)
            {
                Console.WriteLine("Hello World!");
            }
            
            Console.WriteLine("Press any key to continue.....");
            Console.ReadLine();
        }

3. Press F5 to run and see the results.

4. Thank you.

The for-loop statement is used perform a piece of code multiple times as long as the condition set is evaluated to true. Its syntax is:

for(<initialization>;<condition>;<incrementation/decrementation>)

{

                //code to execute

}